update tests

Author: lcnr

src/test/ui/const-generics/const_evaluatable_checked/let-bindings.stderr

@@ -1,8 +1,10 @@
-error: constant expression depends on a generic parameter
+error: overly complex generic constant
   --> $DIR/let-bindings.rs:6:68
    |
 LL | fn test<const N: usize>() -> [u8; { let x = N; N + 1 }] where [u8; { let x = N; N + 1 }]: Default {
-   |                                                                    ^^^^^^^^^^^^^^^^^^^^ required by this bound in `test`
+   |                                                                    ^^^^^^-^^^^^^^^^^^^^
+   |                                                                          |
+   |                                                                          unsupported statement
    |
    = help: consider moving this anonymous constant into a `const` function
 

src/test/ui/const-generics/issues/issue-76595.stderr

@@ -8,7 +8,7 @@ error: constant expression depends on a generic parameter
   --> $DIR/issue-76595.rs:15:5
    |
 LL | fn test<T, const P: usize>() where Bool<{core::mem::size_of::<T>() > 4}>: True {
-   |                                                                           ---- required by this bound in `test`
+   |                                         ------------------------------- required by this bound in `test`
 ...
 LL |     test::<2>();
    |     ^^^^^^^^^